Presently available diagnostic imaging apparatuses for capturing diagnostic images of patients include CT scanners, MRI (Magnetic Resonance Imaging) apparatuses, PET (Positron Emission Tomography) apparatuses, ultrasonic diagnostic apparatuses, CT angiography apparatuses, and MRA (MR angiography) apparatuses. When such a diagnostic imaging apparatus is used, a liquid such as a contrast medium or physiological saline may be injected into a patient. Chemical liquid injectors for automatically performing the injection have been put into practical use.
Such a chemical liquid injector has a liquid injection mechanism includes a driving motor, a slider mechanism and the like, for example. A liquid syringe is removably mounted on the injector. The liquid syringe includes a cylinder member and a piston member slidably inserted in the cylinder member. There are a pre-filled type and a refill type in the liquid syringe.
The liquid syringe of the pre-filled type filled with a liquid within its cylinder member and shipped in wholley sealed by a packing material. In the liquid syringe of the refill type, a user fills a cylinder member with a desired liquid. To simplify the explanation, the following description will be made on the premise that the liquid syringe of the pre-filled type is used.
When the liquid in the abovementioned liquid syringe is injected into a patient, an operator prepares an appropriate liquid syringe for a liquid to be used and takes the liquid syringe out from the packing material. The operator connects the liquid syringe to the patient through an extension tube and sets the syringe on a liquid injection mechanism of a chemical liquid injector. In response to a predetermined operation, the chemical liquid injector relatively moves the piston member and the cylinder member with the liquid injection mechanism to inject the liquid into the patient from the liquid syringe.
In this case, the operator determines the rate at which the liquid is injected and the total quantity of the liquid to be injected in view of the type of the liquid and the like, and then enters data representing the rate and total quantity into the chemical liquid injector. The chemical liquid injector injects the liquid into the patient based on the entered data. For example, when the contrast medium is injected as the liquid, the contrast medium changes the degree of contrast in the patient to allow the diagnostic imaging apparatus to capture a good diagnostic image of the patient.
Some chemical liquid injectors are capable of injecting physiological saline in addition to the contrast media into the patient. In such a chemical liquid injector, the operator enters, as desired, an instruction to inject the physiological saline following the completion of the injection of the contrast medium, together with data representing the injection rate and total quantity of the physiological saline, into the chemical liquid injector.
The chemical liquid injector injects the contrast medium into the patient based on the entered data and then automatically injects the physiological saline. The subsequently injected physiological saline can push the previously injected contrast medium to reduce the consumption of the contrast medium, and also can reduce artifacts in the captured image.
Chemical liquid injectors of the type described above have been devised and applied for patent by the applicant of the present application and the like (see, for example, patent documents 1 and 2 below).
Patent document 1: Japanese laid-open patent publication No. 2002-11096;
Patent document 2: Japanese laid-open patent publication No. 2002-102343.